Superhumps in cataclysmic binaries .10. V1973 Cygni (Nova Cygni 1992)

We report photometry of V1974 Cygni, the remnant of Nova Cygni 1992. A very nearly stable photometric signal with a period of 117.012 (+/-.002) min was present throughout 1993-6, with declining amplitude. This appears to be the underlying orbital period of the binary; at least during 1993, it probably manifested itself through the external heating of the secondary star's atmosphere. We interpret the declining signal amplitude as the result of white-dwarf cooling after the nova outburst. This suggests an e-folding time scale of similar to 80 d for luminosity decline, consistent with the UV flux which probably arises from the heated accretion disk. During 1994-1996 there appeared another photometric signal, far less stable. The period varied in the range 122.4-122.7 min, with an average \P\ of about 10(-6) We interpret this as a ''superhump,'' a common phenomenon in cataclysmic binaries of short P-orb and high accretion rate.